1. Field
Example aspects described herein relate to optical communication, and more specifically, to a method and system for gain tilt compensation over fiber optic cable.
2. Description of Related Art
Optical networks are used to transmit great amounts of data from one place to another. Ability to use multiple wavelengths in an optical fiber has led to increased data transmission rate. However, a multiplicity of optical signals of different wavelengths transmitted through a series of fiber optic cable spans and optical amplifiers will experience different attenuation and gain as a function of wavelength. This phenomenon of gain tilt, where the shorter wavelengths are typically attenuated the most, ultimately reduces the optical signal-to-noise ratio observed at the transponder terminating a particular wavelength. This reduces the ability of the transponder to decode the received signal without errors. Left uncorrected, the longer wavelengths, after passing through a number of spans and amplifiers, can reach power levels that cause the amplifiers to operate in a non-linear fashion. This also degrades the signal quality observed at the terminating transponder, potentially increasing the received error rate. The signal distortion introduced by gain tilt limits the overall length of a fiber optic span before amplification is required and also limits the number of fiber optic span segments that can be cascaded in a fiber optic network.
However, altering the gain distribution for an optical amplifier may cause the optical amplifier to operate in a non-optimal mode and may increase the overall noise introduced by the amplifier. This increased noise can reduce the optical signal-to-noise ratio such that the signal quality is degraded more than if no gain tilt compensation was applied.